Issue 43, 2016

Diamond crystallization and growth in N–H enriched environment under HPHT conditions

Abstract

Advances in understanding the state and transformation of impurity-related defects in natural diamond have been achieved by means of high-pressure and high-temperature annealing experiments. However, the existing literature featuring complex behaviors of aggregated nitrogen and hydrogen-related defect (3107 cm−1 center) has remained controversial. Their formation mechanism during diamond crystallization is still unclear, thus further investigation is required. In this work, we have successfully synthesized a variety of high-quality diamonds containing nitrogen impurities with IaA (nitrogen pairs), IaB (group of four nitrogen atoms around a vacancy) and Ib (single-substitutional nitrogen) characteristics ranging from <1 ppm to 3380 ppm at pressures ranging from 5.0 GPa to 6.3 GPa and temperatures of 1300–1650 °C. Our results provide new experimental evidence for the aggregation of nitrogen impurities (A- and B-centers) during diamond growth. We notice that the hydrogen is easily trapped by nitrogen atoms to form nitrogen–hydrogen complexes (–NH, –NH2, –NH3) when the nitrogen tends to form C-centers in hydrogen-enriched environments. Additionally, we observed that the high reaction temperature and formation of A-centers during diamond growth play important roles in the formation of the 3107 cm−1 center. We believe the current results could be helpful for further understanding and constructing a clear model of impurity-related defects, and thus provide us deeper insights into the genesis of natural diamond.

Graphical abstract: Diamond crystallization and growth in N–H enriched environment under HPHT conditions

Article information

Article type
Paper
Submitted
20 Sep 2016
Accepted
13 Oct 2016
First published
13 Oct 2016

CrystEngComm, 2016,18, 8506-8515

Diamond crystallization and growth in N–H enriched environment under HPHT conditions

X. Liu, X. Jia, C. Fang and H. Ma, CrystEngComm, 2016, 18, 8506 DOI: 10.1039/C6CE02034H

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